This invention relates to an elevator apparatus, and more particularly to an elevator apparatus provided with a guide device which can guide a car without shaking or vibrating it.
Generally, a car of an elevator is guided along a pair of guide rails by guide devices comprising guide slide members and guide rollers, and is driven to run in such a manner as to be held horizontally. At this time, the position of the center of gravity of the car during operation varies in accordance with the distribution of a live load in the car and the distribution of weights of cables for supplying electric power to the car, a compensation rope, etc., which weights vary with time, so that this center of gravity position does not coincide with the axis of suspension of the car. Therefore, the car guide devices, while receiving deflected loads of the car resulting from the deviation of the car suspension axis from its center of gravity position, guide the car.
If the guide rail is bent at a portion thereof, the car is subjected to a forcible excitation or vibration due to this bending through the guide devices. In order to reduce a lateral vibration of the car due to this forcible excitation, the guide device usually guides the car through guide members in the form of a resilient support member such as a spring, a rubber member or the like.
In order to prevent the lateral vibration of the car due to the above-mentioned bending of the guide rail, it is desired to reduce the elastic constant of the resilient support member; however, in order to keep the flexure due to the deflected load of the car to within a predetermined range so as to guide the car safely, the guide member is required to have a predetermined rigidity.
The prior art satisfying the above two functions required for the guide device for the elevator apparatus includes, for example, Japanese Patent Publication No. 58-39753 and Japanese Unexamined Patent Publication No. 63-87482.
These prior art techniques are directed to a system in which guide portions of a magnetic guide type are used to guide a car in a non-contact manner.
Another example of the prior art is known from Japanese Unexamined Patent Publication No. 58-104885. In this prior art, the axis of suspension of a car is deviated from the position of its center of gravity toward an entrance-exit of the car, and guide devices guide the car in a manner to urge the car against guide rails, thereby preventing a lateral vibration of the car.
In the above prior art technique using the magnetic guide system (Japanese Patent Publication No. 58-39753 and Japanese Unexamined Patent Publication No. 63-87482), magnetic controllers are required respectively for the guide devices provided in the rail gauge direction of a pair of guide rails and on opposite sides of a plane in which the guide rails are disposed. A displacement of the car due to a bending of the guide rail is detected based on a reference line extending from an uppermost stair to a lowermost stair, thereby controlling the position of the car relative to the guide rails. Therefore, this system is quite expensive, and therefore has a problem that it is not easily applied to ordinary elevators.
In the above prior art (Japanese Unexamined Patent Publication No. 58-104885) in which the suspension axis of the car is deviated from the position of its center of gravity toward the entrance/exit of the car, there is encountered a problem that vibration of the car due to a bending of the guide rail can not be prevented.